Find the genetic distances between the three genes | Homework Help

Drosophila strain Ly (Lyra), Sb(stubble) and br (brown) wascrossed with a wild type strain. The F1 females were crossedto + ,+, br homozygous males. The F2 were collected andcounted. The table below shows the results obtained.
Phenotype offlies         Number
Ly, Sb,br                     404
Wildtype(+,+,+)           422
Ly, +,+                        18
+, Sb,br                        16
Ly, +,br                        75
+, Sb,+                        59
Ly, Sb,+                        4
+, +,br                           2

a) Draw a diagram to show the genetic crosses involved.
b) Find the genetic distances between the three genes.
c) Calculate the coefficient of coincidence and alsointerference.